fix(clipboard): restore cleanup when legacyCopy's select() throws

web/src/design-system/helpers/clipboard.test.ts

@@ -99,4 +99,15 @@ describe("copyToClipboard", () => {
   it("does not report success where no clipboard mechanism exists at all", async () => {
     expect(await copyToClipboard("openai:gpt-4o", undefined)).toBe(false)
   })
+
+  it("removes the scratch textarea even when select() throws (#1149)", async () => {
+    // The textarea holds the plaintext, often a one-time API key, so a throw
+    // between the append and the removal leaves a credential in the DOM.
+    vi.spyOn(HTMLTextAreaElement.prototype, "select").mockImplementation(() => {
+      throw new Error("detached document")
+    })
+
+    expect(await copyToClipboard("provider secret", undefined)).toBe(false)
+    expect(document.querySelectorAll("textarea")).toHaveLength(0)
+  })
 })

web/src/design-system/helpers/clipboard.ts

@@ -42,20 +42,24 @@ function legacyCopy(text: string): boolean {
     document.activeElement instanceof HTMLElement
       ? document.activeElement
       : null
-  source.select()
 
   let copied = false
   try {
+    source.select()
     copied = document.execCommand("copy")
   } catch {
+    // Covers select() too, not just execCommand: a throw there is still a copy
+    // that did not happen, and the caller reads the return value to say so.
     copied = false
+  } finally {
+    // In a finally: the textarea holds the plaintext, so it must not outlive a
+    // throw above it (#1149).
+    source.remove()
+    if (selection && previous) {
+      selection.removeAllRanges()
+      selection.addRange(previous)
+    }
+    previousFocus?.focus()
   }
-
-  source.remove()
-  if (selection && previous) {
-    selection.removeAllRanges()
-    selection.addRange(previous)
-  }
-  previousFocus?.focus()
   return copied
 }